Not really sure what the DND was using them for, but they are dimension-ally the right size for the 60mm mortar. As far as I know, Canada merely used the wooden crate for the old 60mm mortar, but Pelican lists the 60mm mortar case in their Canadian Military Products brochure.
http://www.customcaseco.c/pdf/Pelica..._Brochure2.pdf
Pelican's listing is for the M224 Mortar, which Canada did not adopt (yet) but they note it will fit other similar 60mm mortars. I have assembled a M19 Canadian mortar and would like a chest to transport it in. I do not have the wooden chest, and the wooden chest is not particularly robust for that matter. To buy one of these chests from Pelican, or one of their distributors is very expensive. Prices range from $1200-$3500, depending on the supplier. It makes the $60 each they are currently selling for from the depot seem like a pittance.
Charlie: Pelicans can fly on their own as a self contained unit...they don't need luggage